Many larger vessels including luxury yachts and sports fishing boats are constructed with a hull and other structural components including composite materials such as fiberglass. Conventionally, formation of the hull, for example, begins with the hand construction of a "positive" mold or "plug" typically made of wood or the like. The desired contours, size and other physical aspects of the finished hull are replicated in the positive mold. The next step is to form the "negative" mold, which historically has been accomplished by hand laying a first layer of fiberglass or other composite material directly onto the positive mold sometimes followed by a core layer made of various substrates which is affixed to the first fiberglass layer. Finally, a second fiberglass layer is applied by hand onto the core, or onto the first fiberglass layer if no core is employed, to form the finished negative mold. The first layer of fiberglass of the negative mold forms a continuous mold surface which matches the shape of the positive mold.
In current practice, the negative mold is formed in one section or two large half sections, i.e., a starboard half section including half of the bottom and the entire starboard side of the hull, and a port half section including the other half of the bottom and the entire port side of the hull. These half sections are connected together to form a complete negative mold, having a substantially continuous mold surface from the bow of the vessel to the stern. The hull is formed by laying up first layers of composite material directly onto the mold surface of the negative mold, followed by a core, usually made of a framework of balsa wood or foam material, and then second layers of composite material laid up on the exposed surface of the core. Once the composite material has cured, the entire hull is lifted from the negative mold by an overhead crane or the like, and moved to another site within the manufacturing facility for further construction of the vessel. The negative mold is disassembled into its two half sections, and stored for re-use.
The method and apparatus for constructing the hull of vessels described above has a number of limitations and disadvantages. One problem relates to scale. Many luxury yachts and larger sport fishing vessels are in the range of fifty to one hundred ten feet long or more. It can be appreciated that the sheer size and height of a single section, or port and starboard half sections, forming the negative mold present a number of difficulties with handling and storage. A very large facility is required to store mold section or half sections of the size noted above, and if the manufacturer builds a number of different vessel sizes and/or models, the storage and handling problems increase dramatically. In many instances, manufacturers are limited to constructing only one vessel at a time because the rest of the space in their manufacturing facility is taken up with the storage of the negative mold sections.
Another significant problem with the negative molds described above is that they cannot be utilized to construct hulls of different sizes and/or shapes. As described above, current negative molds are formed in continuous starboard and port half sections, which are interconnected at the center, thus allowing only one vessel hull to be formed therefrom. When the manufacturer desires to change the hull shape or size, e.g., width, length or height, a completely new negative mold must be constructed in accordance with the method outlined above. This is an extremely expensive and time consuming operation, and results in the formation of a new set of negative mold half sections which themselves take up valuable storage space in the facilities of the vessel manufacturer.
A further problem with the method and mold apparatus described above is related to handling of the vessel hull once it is formed. As described above, the bottom and sides of the vessel hull are formed against the mold surface of the negative mold, and allowed to cure. In order to separate the hull from the negative mold, an overhead crane or similar device must be utilized to lift the hull from the negative mold and move it to another location for further handling. This requires a manufacturing facility having comparatively high ceilings, and an expensive, heavy-duty overhead crane capable of lifting the entire hull.